Electric valve circuit



Jul 18, 1939. H. w. LORD ELECTRIC 'VALVE CIRCUIT Original Filed April24, 1937 Gaa'eau: f Je Fig.8.

d y P m If. I. nwm eddt vmA rmwW lm .l H L! Patented July 18, 1939UNITED STATES PATENT OFFICE 2,166,309 ELECTRIC vALvE CIRCUITHaroldW.Lord. Schenectady, N. Y., asslgnor to General Electric Company,a corporation of I, New York;

Application awn 24.1937, Serial No. 138,809

Rcnewedl'ebruary ll, 1938 rac m. gicl. 25041 My invention relates toelectric valve circuits and more particularly to control or excitationcincuits for electric valve translating apparatus.

Heretofore there have been devised numerous;

type of control is particularly desirable in circuits,

such as welding circuits, where it is important to effect energizationof an associated load circuit during only a portion of a half cycle ofapplied voltage.

tivity of the electric valve means.

art arrangements where it has been attempted to combine these twofeatures in a contr' for electric valve means, theapparacusnm providingthis type of control haslbeen complicated in construction andarrangement and has necessitated the use of control apparatusinordinate'in size and rating as compared to theratlng of the main orpower apparatus to be controlled.

It is an object of my invention-to provide a new and improved. electricvalve circuit.

It is another object of my invention to provide a new and improvedcontrolor excitation circuit for electric valve means U l It is afurther object of my invention to provide a new and improved electricvalve translating circuit for transmitting energy between alternatingcurrent circuits or between alternating current circuits and directcurrent circuits.

It is a still further object of my invention to provide an improvedcontrol circuit for electric valve means of the type employing anionizable medium which is simple in construction and arrangement.

In accordance with the illustrated embodiment of my invention, I providea new and improved control circu t for electric valve means. Theconductivity of the electric valve means is controlled by impressing onthe control members thereof alternating voltages of peaked wave formadjustable in phase to control the amount of energy transferred to anassociated load circuit. The

In the control 01' q Furthermore, it has been found to be"particularly'desirable to employ alternating voltages of peaked waveform to control the ccnduc- In the prior control circuit for thefvalvemeans includesa source of alternating voltage of peaked wave form and apair of, circuits arranged to conduct current alternately and whichimpressaltiamating voltages ofpe'aked wave form. on the control 5members of the electric valves; Each of the circuits includesapunidirectional conducting path, such asan electric valve or a contactrectifying device. A single electronic discharge device of the typeemploying an ionizable medium is'connected in serie's relation with theunidirectional conducting 'paths tocontrol the current transmittedthereby and hence to effect control of the alternating voltages ofpeaked wave form impressed onthe" control members of the electric valvemeans. A control circuit is employed to impress on a controlme'm'berofthe electronic discharge devlce a periodic electricalquantity; 'such asa periodic alternatingvoltagr to. render the discharge device conductivefor a predetermined number of half cycles of voltage of the supplycircuit. As ai'urther feature of my invention, I provide means forintroducing in the control circuit' for the electronic dischargedevice avoltage to assure that the discharge device is rendered conductive atthe beginning of each of the numberof half cycles of conductionestablished by I the control or timing circuit, in this way providi'nganarrangement fol-locking in the excitationv circuit toa'ssjure positiveand precise'ccntrol even :though the rate of change of the periodiccontrol I voltage is relatively small.

For. a better understanding of my invention, reference may be had to thefollowing description taken in connection with the accompanying drawing,and its scope will be pointed out in the appended claims. Fig. 1 01' theaccompanying drawing diagrammatically represents an embodiment of myinvention as applied to an electric valve system for energizinga weldingcircuit. 40 and Fig. 2 represents certain operating characteristicsthereof.

In Fig. l of the accompanying drawing my invention is diagrammaticallyshown as applied to an electric valve translating circuit for transmit-4.5 ting energy from an alternating current circuit I to a load device,such as a transformer 2. The transformer 2, for the purpose ofillustration, is shown as being arranged to supply a welding or loadcircuit 3. In order to control the transfer of energy from thealternating current circuit i to the load circuit 3, I may employ a pairof op- .positely disposed electric valves 4 and 5 which are arranged toconduct current alternately. The electric valves 4 and 5 are preferablyof the cathode I and a control member The electric4and|maybeconnectcdacrossaseci| oi an inductive device to conandhencetoccnirolthemergytranaferredirom them totheloadcircuit2.Itiscvalve means4 device.suchasatransiormer.iihavingapairoiprimarywindingsfland i2,apairofseccndary windingsilandllandatertiarywindin i|. Thssecondarywindingsfland ilareconnectedto control members of electric valves 4 and respectively. A negativeunidirectional biasing mltage may be impressed on control members|oielectricvalvea4and|byanymitabiemeanssuchasbatteriesitandsuitablecurrcntlimiting resistancesIImaybeecnnectedin-series relationwiththeasscciated thecontrolmembers.Inordertoimpcseapredominately resistive load across the secondarywindings i4 and il oitransformer ",1 connectresistancesilacrcsstbesewindings.

Inordertosupplytotheprimarywindings l2 and i2 of transformer ii suitablecurrentstoinduceinthesecondarywindings i4and llalternating voltages oipeaked wave iorm, I employa source of alternating voltage ofsubstantially peaked wave form which may be furnished by a. saturableinductive device 2| having a core member 2i, a saturable section 22, aprimary exciting winding 2| and secondary windings 24 and 2| in whichthere is induced an alternating voltage of peaked wave form. While Ihave chosen to repraent this source of alternating voltage of peakedwave form as comprising a saturable inductive device. it is to beunderstood that if desirable I may employ any other conventionalarrangement. Interposed between the inductive de-' vice 2| and thetransformer ii there is provided a pair of circuits including conductors2|. 2! and 2|, conductor 2| being connected to the upper terminal oiprimary winding i2 and conductor 2| being connected to the lowerterminal of primary winding i|. Each of the circuits includes aunidirectional conducting path These unidirecticnal conducting paths maybe aiiorded by electronic discharge devices or by the use of suitablecontact rectifying means. In the particular arrangement shown in thedrawing, I have chosen to represent these unidirectional conductingpaths as comprising an electronic discharge device 2| having anodes 2|and ii and a cathode 22. A suitable cathode heating transformer 22having a primary winding 24 and a secondary winding 2| may be employedto energize the cathode 22 of the discharge device 2|.

Connected in series relation with the undirectional conducting paths tocontrol the current transmitted thereby, I provide an electronicdischarge device 2|. preferably oi the type employot the inductivedevice secondarywindingsand.

and including an anode 21, a cathode 2| and a control member 2|. Asuitable cathode heating transformer 4| having a primary winding 4! anda second ry winding 42 may be associated with the electronic dischargedevice 2| for heating the cathode thereof.

As an agency for rendering the electronic discharge device nonconductiveat the end of each half cycle oi voltage of peaked wave iorm or at theend oi each impulse of current conducted thereby, I employ acapacitance4| connected in series relation with the electronic discharge device Aresistance 44 is connected across the capacitance 42 and mes as adischarge circuit for the capacitance. and a suitable impedance element.such as a resistance 4|, is connected acrol the serially-connectedcapacitance 42 and the electronic discharge device 2| for impressing onthe anode 21 thereof a negative transient potential to render thedischarge device nonconductive at the end oi each half cycle oiconduction. This arrangementfor controlling an electric valve means thetype employing an ionisable medium for a full wave rectifying circultildiM-IOSGG and broadly claimed in Letters Patent No. 2,098,051 grantedNovember 2, 1937, on my application Serial lid-69,243, tiled March 16,1986, and assigned to the assignee-oi the present application. Thisapplication is made to protect the iurther invention which the applicantbelieves to be present in the apparatus set forth in the claims hereoiover and beyond the claims set forth in the aforementioned LettersPatent.

To impress on control member 22 of electronic discharge device 2| aperiodic timing quantity, such as a periodic voltage. to render theelectronic discharge device 2| conductive for a predetermined intervaloi time and hence to effect energisaticn of the load circuit from thealternating current circuit I tor a corresponding interval of time, Iemploy a control or timing circuit 4|. The timing circuit 4| includes asource of unidirectional voltage 41, a .voltage divider including aresistance 4| having adjustable conan ionirable medium, such as a gas ora vapor,

and includes an anode 54, a cathode 55, and a control member Aninductance 51 is connected' in series relation with the electric valve22 to impress thereon a negative transient voltage to render theelectric valve 52 periodically nonconductive to permit the controlmember it to regain control at the end of each discharge of thecapacitance Ii. Interposed between the adiustable contact of the voltagedivider and the control member l| of electric valve 52 there isintroduced, by the agency of a transformer an alternating voltageproperly correlated in phase and frequency relative to the voltage ofthe alternating current circuit I so that the electric valve means 4 and5 are controlled at the proper time relative to the voltage of supplycircuit i. Transiormer Il may be oi the type designed to furnish analternating voltage of peaked wave iorrn to render the electric valve 52conductive at a predetermined instant during the voltage oi thealternating current circuit I, in this way to effect accurate control ofthe times at which the electric valves 4 and i are rendered conductive.Primary winding oi transformer 56 may be energized from any suitablesource of alternating current correlated inphase and frequency withrespect to the voltage of the alternating current circuit I. In theparticular arrangement shown in Fig. 1, the transformer 58 is shown asconnected to the alternating cur rent circuit I through any conventionalphase shifting arrangement such as a rotary phase shifting device 50. Acircuit controlling means, such as a switch 6|, may be interposedbetween the source of direct current 41 and the control circuit 4 todeenergize control circuit 46 to prevent energization of the loadcircuit 3.

To introduce in the control or excitation circuit 46 Ior the electronicdischarge device 36 a positive voltage to render the electronicdischarge device 36 conductive at the beginning oi. each half cycle ofvoltage of peaked wave form provided by the device 20, I provide acircuit 61. The circuit 62 may include an impedance element 63 connectedin series relation with control member 39 0! discharge device 36. Asuitable energy storage device, such as a capacitance 64, is connectedin parallel relation with the impedance element 68; and a rectifier 65is energized from the tertiary winding l6 oi transformer II. Therectifier 65 is shown as being of the full wave rectiiying type. but itis to be understood that other types of rectiflers may be employed.Since the tertiary winding I6 oi transformer I I is inductivelyassociated with the primary and secondary windings, it is to be notedthat the volt-- of voltage of peaked wave form during the intervalestablished by the control circuit 46.

As an agency for controlling the phase of the alternating voltage ofpeaked wave form provided by the saturable inductive device 20 I employany conventional phase shifting arrangement such as the rotary phaseshiiter 66 which'may be manually or automatically operated. The phaseshifter 66 is shown as being energized from the alternating currentsupply circuit I and it is to be understood that any other suitablesource of alternating voltage of the proper frequency may be employed ifdesired.

The general principles of operation of the embodiment of my inventiondiagrammatically shown in Fig. 1 will be explained by considering thesystem when energy is being transmitted from the alternating currentcircuit I to the load circuit 3 through the inductive device 9 and thetransformer It will be well understood by those skilled in the art thatthe voltage impressed on the load circuit by the electric valve means 4and 5 will be increased as the time of ignition of the valves 4 and I isadvanced toward the beginning of each positive half cycle of voltageimpressed on the associated anodes, and that the voltage so impressed bythe electric valves will be decreased as the electric valves arerendered conductive at later times during the respective halt cycles ofthe voltage applied to the anodes. For example, when the load isresistive and when the voltages ol'peaked wave form impressed on ,thecontrol members 8 of electric valves 4 and 6 occur at the beginning ofthe positive half cycles of voltage, the current transmitted by theelectric valves 4 and 5 will be maximum and the impedance offered by theinductive device 9 will be minimum to eiiect a maximum power transferfrom the alternating current circuit I to the load circuit 3. It will beunderstood that as the voltages of peaked wave form impressed on controlmembers 8 are retarded, the current transmitted by electric valves 4 and6 will be decreased to effect an increase in the impedance offered bythe inductive device 9 to decrease the power transfer from the supplycircuit I to the load circuit 3.

Let it be assumed that the switch BI is closed and that the control ortiming circuit 46 is adjusted so that the periodic voltage impressed oncontrol member 39 of electronic discharge device 36 is suilicientlypositive relative to the cathode 38 to render discharge device'36conductive for a predetermined number of half cycles of alternatingvoltage supplied by the saturable inductive device 20 or for apredetermined number of half cycles of the voltage of supply circuit I.The electric valve 53 will be rendered conductive at a predeterminedinstant during a cycle of voltage of circuit I to render electric valves4 and 6 conductive at the proper instants during the respective haltcycles of voltage applied thereto. Since the two circuits includingconductors 28, 21 and 28 are arranged through the discharge device 29 toconduct current alternately, the voltage appearing between anode 31 andcathode 3! of electronic discharge device 36 will correspond to thatrepresented by curves A of Fig. 2. The rectification of the alternatingvoltage oi peaked wave form provided by saturable inductive device 20 iseffected by the electronic discharge de- Til vice 2!. If it be assumedthat the periodic con trol voltage provided by control circuit 46becomes sumciently positive at a time corresponding to the position ofline 0, electronic discharge device 36 will be rendered conductive atthis time and will conduct current during the interval a--b. Curve Brepresents the voltage appearing across anode 31 and cathode 38 ofdischarge device 36 during the interval of conduction established bycontrol circuit 46. At time b the electronic dis charge device '36 willbe rendered nonconductive by virtue oi the negative transient voltageimpressed on anode Ill thereof by means of the capacitance 43 and theresistance 46. During the interval b-c this transient voltage will decayexponentially by virtue of the discharge of capacitance 43 through theshunt connected resistance 44. At time c the electronic discharge device36 is again rendered conductive and transmits current during theinterval cd, and this cycle of operation is repeated so long as thepcri- 'odic control voltage provided by circuit 46 remains sufficientlypositive relative to the cathode 38. It is to be noted that the periodoi the periodic control voltages provided by control circuit 46 isdetermined principally by the time constant of the circuitv includingcapacitance SI, resistance 52 and the setting of adjustable contact 50of circuit 46.

Curve C of Fig. 2 represents the voltage which would appear across anodel1 and cathode II of electronic discharge device 36 if an alternatingvoltage 01' sinusoidal wave form were employed instead of an alternatingvoltage of peaked wave form, and curve D represents the voltage whichwould appear across anode 31 and cathode 36 of this discharge deviceduring the interval of con duction established by the timing circuit 48it discharge device 36 were rendered conductive at time c. The negativepeaks represented by portions 1 of curve D are due.to capacitance l3 andresistance 46.

Circuit 82, which is energized from the tertiary winding it oftransformer II which in turn is energized in accordance with thetransfer of energy to the control circuits for electric valves .4 and O,impresses a positive voltage on control member I! of electronicdischarge device 38 to lock in the discharge device ll to assure that itis rendered conductive at the proper time during each half cycle ofvoltage impressed. thereon, even though the rate of change of theperiodic control voltage is relatively small. In this manner there' isprovided an arrangement for assuring a positive and precise control ofthe electronic discharge device 80. j

By the proper adjustment of the conhui aircuit I, the period duringwhich enlgy is supplied to the load circuit 8 from the supply circuit Imay be accurately controlled and this control is en'ected by controllingthe number of impulses of voltage of peaked wave form which areimpressed on control members I of electric valves 4 and I. So long asthe switch is maintained in the closed circuit position, control circuit48 will function to supply a periodic control voltage to renderelectronic discharge device 36 conductive for a predetermined time andhence to render electric valves l and 6 conductive during -acorresponding interval of time. The ratio a! timeon to time-oi! ofelectronic discharge device 3' may be controlled by adjusting contact49, in this way providing an arrangement for controlling the ratio oftime-on to time-oil of electric valves 4 and 5. The time of the weldingcycle, that is, the

' sum of the time-on and the-time-oif intervals may be controlled byadjusting resistance II. Furthermore, by adjustment of the rotary phaseshifter 86, the portion of each half cycle of voltage of circuit iduring which electric valves l and conduct current may be controlled tocontrol the amount of energy transmitted to the load circuit 3. Forexample, if it is desired to effect energization of a welding circuitduring a' predetermined number of half cycles, this control may beeffected by the adjustment of control circuit 40 to render electricvalves 4 and i conductive during a corresponding interval of time.Moreover, by the adjustment of rotary phase shifter C, the amount ofenergy transmitted during that interval may be controlled by thisselective mane adjustment of the voltages impressed on control membersI. e

While I have shown and described my invention as applied to a particularsystem of connections and as embodying various devices diagrammaticallyshown, it will be obvious to those skilled in the art that changes andmodifications may be made without departing from my invention, and I,therefore, aim in the appended claims to .cover all such changes andmodifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In combination, an alternating current supply circuit, an alternatingcurrent load circuit, electric valve means interposed therebetween forcontrolling the transfer of energy from said supply oircuit to said loadcircuit and being provided with a control member for controlling theconductivity thereof, and a control circuit for energizing said controlmember comprising a source-of alternating voltage of peaked wave form,an induc-' tive device having a pair of primary windings and a secondarywinding connected to said control member, a pair of circuits energizedfrom said source of voltage of peaked wave form each associated with adifferent one of said primary windings and each including aunidirectional conducting path and arranged to transmit currentalternately, an electronic discharge device of the type employing anionizable medium and having a control member and being connected inseries relation with said unidirectional conducting paths forcontrolling the transfer of current therethrough and means connectedacross said electronic discharge device to render said devicenonconductive at the end of each half cycle of conduction to permit saidcontrol member to obtain control. 2. In combination, an alternatingcurrent supply circuit, an alternating current load circuit, electricvalve means for controlling the transfer of energy between said circuitsand including a control member for controlling the conductivity thereof,a transformer having a pair of primary windings and a secondary windingconnected to said control member, an inductive device energized fromsaid alternating current circuit for providing an alternating voltage ofpeaked wave form, a pair of circuits connected between said inductivedevice and said primary windings of said transformer and each includinga unidirectional conducting path and arranged for transmitting currentalternately, an electronic discharge device of the type employing anionizable medium and having a control member and being connected inseries relation with said conducting paths for rendering said electronicdischarge device nonconductive at the end of each half cycle ofconduction, a control circuit for energizing said control member of saidelectronic discharge device, and means energized in accordance with thecurrent conducted by said primary windings for introducing in saidcontrol circuit a voltage to maintain said electronic discharge deviceconductive during the interval of conduction established by said controlcircuit.

3.'In combination, an alternating current supply circuit, a secondalternating current circuit,

'electric translating apparatus interposed therebetween comprisingarr-inductive device and an electronic discharge device of the typeemploying an ioniaable medium and having a control member forcontrolling the transfer of energy between said supply circuit and saidsecond circult, means for rendering said discharge device nonconductiveat the end of each half cycle of voltage of said supply circuit, acontrol circuit for impressing on said control member a periodic voltageto render said discharge device conductive for a predetermined number ofhalf cycles of said supply circuit, and means responsive to the transferof energy through said inductive device for introducing in said controlcircuit a positive voltage to render said discharge device conductive atthe beginning of each of said number of half cycles of conductionestablished by said control circuit.

4. In a control circuit for an electric valve means having a controlmember, the combination of a source of alternating voltage of peakedwave form, a transformer having a pair of primary windings and asecondary winding connected to said control member, a pair of circuitsinterposed between said source and said primary windings and eachincluding a unidirectional conductinll amaaoo path and arranged fortransmitting current a1- ternately, an electronic discharge-device ofthe type employing an ionizable medium having a control member and beingconnected in series relation with said unidirectional conducting paths,

means connected across said discharge device for rendering said devicenonconductive at the end of each impulse of current conducted therebyand means for energizing said control member of said discharge device torender said device conductive for a predetermined interval of time.

5. In an excitation circuit for an electric valve means having a controlmember, the combination of a source of alternating voltage of peakedwave form, a transformer having a pair of primary windings and asecondary winding connected to said control member, a pair of circuitsinterposed between said source and said primary windings and eachincluding a unidirectional conducting path and arranged for transmittingcurrent alternately, an electronic discharge device of the typeemploying an ionizable medium and having a control member and beingconnected in series relation with said unidirectional paths forcontrolling the current conducted thereby, means comprising acapacitance connected in series relation with said discharge device andan impedance element connected across said discharge device and saidcapacitance for rendering said device nonconductive at the end of eachhalf cycle of conduction, and a control circuit for impressing on saidcontrol member of said discharge device a periodic timing quantity torender said discharge device conductive for a predetermined number ofhalf cycles of voltage of said source.

6. In a control circuit for an electric valve means having a controlmember, the combination of a source of alternating voltage of peakedwave form, a transformer having a pair of primary windings and asecondary winding connected to said control member, a pair of circuitsinterposed between said source and said primary windings fortransmitting current alternately and each including a unidirectionalconducting path, an electronic discharge device of the type employing anionizable medium and having a control member and being connected inseries relation with said unidirectional conducting paths to control thenumber of impulses of voltage impressed on said control member of saidelectric valve means, means connected across said discharge device forrendering said device nonconductlveat the end of each half cycle ofconduction, a circuit for providing a periodic timing quantity forrendering said discharge device con-.- ductive for a predeterminednumber of half cycles of voltage of said source, and means responsive tothe transfer of current through said primary windings for impressing onsaid control member of said discharge device a positive voltage torender said discharge device conductive at the beginning of each of saidnumber of half cycles of conduction established by said control circuit.

-relation with a diflerent one of said primary windings and a differentone of said pair of circuits and an electric valve means connected inseries relation with said unidirectional conducting paths forcontrolling the energy transmitted by said circuits, said electric valvemeans being of the type employing an ionizable medium and having acontrol member for controlling the conductivity thereof, means connectedacross said electric valve means for impressing thereon a transientvoltage for rendering said electric valve means nonconductive at the endof each half a cycle of conduction, a control circuit for energizlatingapparatus interposed between said circuits including an inductive devicehaving a pair of primary windings and a secondary winding connected tosaid second circuit, a pair of circuits connected between said supplycircuit and said primary windings and each including a unidirectionalconducting path, said pair of circuits being arranged to conduct currentalternately through the associated unidirectional conducting path, anelectronic discharge device, of the type employing an ionizable mediumand having a control member, connected in series relation with saidunidirectional conducting paths for controlling the current transmittedthereby, means connected across said discharge device for rendering saiddischarge device nonconductive at the end of each half cycle ofconduction, a control circuit for energizing said control member torender said discharge device conductive for a predetermined number ofhalf cycles of voltage of said supply circuit and means for introducingin said control circuit a voltage to render said discharge deviceconductive at the beginning of each of said number of half cycles ofconduction established by said control circuit.

9. In combination, an alternating current supply circuit, a load device,a pair of oppositely disposed electric valve means interposed betweensaid supply circuit and said load device for controlling the transfer ofenergy therebetween, said electric valve means each being provided witha control member for controlling the conductivity thereof, a source ofalternating voltage of peaked wave form, a transformer having a pair ofprimary windings, a pair of secondary windings each connected to thecontrol member of a different one of said electric valve means and atertiary wind ing, a pair of circuits for connecting said primarywindings to said source and each including a unidirectional conductingpath, said pair of circuits being arranged to transmit currentalternately to induce in said secondary windings a voltage of peakedwave form, an electronic discharge device of the type employing anionizable medium and having a control member for controlling theconductivity thereof, means connected across said discharge device forrendering said device nonconductive at the end of each half cycle ofconduction, a control circuit for impressing a periodic timing voltageon said control member of said discharge device to render said deviceconductive for a predetermined number of half cycles or voltage or! saidsource and to render said electric valve means conductive for acorresponding interval of time, and means for introducing in saidcontrol circuit a voltage to render said discharge device conductive atthe beginning of each of said number or half cycles of conductionestablished by said control circuit comprising a resistance connected inseries relation with said control member oi said discharge device, acapacitance connected in parallel relation therewith and a rectifierenergized by said tertiary winding for charging said capacitance.

10. In combination, an alternating current supply circuit, a loadcircuit, electric valve means interposed between said circuits includinga control member for controlling the transfer or energy between saidcircuits, and means for energizing said control member to render saidelectric valve means conductive for a predetermined number of halfcycles of voltage of said supply circuit and to maintain said valvemeans nonconductive tor a predetermined interval oi time thereaftercomprising a source of alternating voltage of peaked wave form, aninductive device having a pair of primary windings and a secondarywinding connected to said control member for impressing thereon analternating voltage of peaked wave form, a pair of circuits interposedbetween said source and said primary windings for conducting currentalternately and each including a unidirectional conducting path, anelectronic discharge device, of the type employing an ionizable mediumand having a control member, for controlling the current transmitted bysaid pair of circuits, a circuit for rendering said discharge devicenonconductive at the end oi each halicycle of voltage of said source anda control circuit for impressing a periodic voltage on said controlmember or said discharge device.

11. In combination, an alternating current supply circuit, a loadcircuit, electric valve means interposed between said circuits includinga control member for controlling the transfer of energy between saidcircuits, a source of alternating voltage oi peaked wave form, aninductive device having a pair or primary windings and a secondarywinding connected to said control member for impressing thereon acontrol voltage, a pair or circuits interposed between said source andsaid primary windings for conducting current alternately and eachincluding a unidirectional conducting path, an electronic dischargedevice of the type employing an ionizable medium and having a controlmember, for controlling the current transmitted by said pair ofcircuits, means for rendering said discharge device nonconductive at theend of each half cycle of voltage of said source, a control circuit forrendering said discharge device conductive for a predetermined number ofhalf cycles of voltage of said supply circuit, and means for controllingthe phase oi said alternating voltage of peaked wave form to control thetime, during each halt cycle or voltage of said supply circuit. at whichsaid electric valve means is rendered conductive.

12. In combination, an alternating current supvalve means for impressingthereon control voltages, means for supplying an alternating voltage ofpeaked wave form comprising a saturable inductive device energized fromsaid supply circuit, a pair of circuits connected between said inductivedevice and said primary windings and each including a unidirectionalconducting path, said circuits being arranged to conduct currentalternately, an electronic discharge device connected in series relationwith said unidirectional conducting paths and including a control memberfor controlling the conductivity thereof, means for rendering saidelectronic discharge device nonconductive at the end of each half cycleof voltage of peaked wave form, a control circuit for rendering saiddischarge device conductive for a predetermined number of half cycles ofvoltage of said supply circuit, and means for shifting the phase of saidalternating voltage of peaked wave form to control the phase of saidcontrol voltages to control the time during each half cycle of voltageof said supply circuit at which said electric valve means are renderedconductive.

13. In combination, an alternating current supply circuit, a loadcircuit, electric valve means connected between said circuits fortransmitting power therebetween and including a control member forcontrolling the conductivity thereof, an excitation circuit forenergizing said control member comprising means for producing a periodicvoltage of peaked wave form, means connected between said control memberand said last mentioned means and comprising a serially connectedunidirectional conducting device having an anodecathode circuit and anelectronic discharge valve having an anode, a cathode and a controlmember, the anode-cathode circuits of said unidirectional conductingdevice and said electronic discharge valve being connected in seriesrelation with each other and connected to be energized from said meanswhich produces a periodic voltage of peaked wave form, means forenergizing said second mentioned control member to effect energizationof said load circuit during a predetermined interval, and means forcontrolling the phase of said periodic voltage to control the amount ofenergy transmitted to said load circuit during said interval.

14. In combination, an alternating current supply circuit, a loadcircuit, and apparatus for producing a train of electrical impulseshaving a predetermined phase relation with respect to the voltage oisaid supply circuit and comprising means for producing a periodicvoltage of peaked wave form, means connected to said last mentionedmeans and comprising a serially-connected unidirectional conductingdevice having an anode-cathode circuit and an electronic discharge valvehaving an anode, a cathode and a control member, the anode-cathodecircuits of said unidirectional conducting device and said electronicdischarge valve being connected in series relation with each other andconnected to be energized from said means which produces a periodicvoltage of peaked wave form, means for energizing said control member toeifect energization or said load circuit during a predetermined intervalof time and means for controlling the phase of said periodic voltage. I

15. In combination, an alternating current supply circuit, a loadcircuit, electric valve means connected between said circuits fortransmitting power therebetween and including a control member forcontrolling the conductivity thereof, an excitation circuit forenergizing said control member comprising a saturable inductive deviceenergized from said alternating current circuit for producing a voltageof peaked wave term, means connected between said inductive device andsaid control member and comprising a serially-connected unidirectionalconducting device having an anode-cathode circuit and an electronicdischarge valve having an anode, a cathode and a control member, theanode-cathode circuits of said unidirectional conducting device and saidelectronic discharge valve being connected in series relation with eachother and connected to be energized from said means which produces aperiodic voltage 01' peaked wave form, means for energizing said secondmentioned control member to eflect energization of said load circuitduring a predetermined interval, and phase shifting means interposedbetween said saturable inductive device and said supply circuit forcontrolling 20 the phase of said periodic voltage to control the amountof energy transmitted to said load circuit during said interval.

16. In combination, an alternating current supply circuit, a secondalternating current circuit, electric translating apparatus interposedtherebetween and comprising an inductive device and an electronicdischarge device having a control member for controlling the transfer ofenergy between said supply circuit and said second circuit, a controlcircuit for impressing on said control member a periodic voltage torender said discharge device conductive for a predeterminednumber'oi'hali' cycles of the voltage of said supply circuit, and meansresponsive to the transfer of energy through said inductive device forintroducing in said control circuit a positive voltage to render saiddischarge device conductive at the beginning of each of said number ofhalf cycles of conduction established by said control circuit.

- HAROLD W. LORD.

